The peyote cactus, Lophophora williamsii, has a long history of use as a hallucinogen.Its activity is due to the alkaloid, mescaline. Many other cacti, used by American Indians, have reputed stimulant and hallucinogenic properties. Mescaline is found in several South American cacti, primarily Trichocereus species, that have folklore uses in Peru and Ecuador as hallucinogens. Mescaline analogues and related tetrahydroisoquinoline alkaloids, with possible psychotropic activity have been found in other cacti, e.g., the "Dona Ana" cactus, Coryphantha macromeris. Little phytochemical attention has been directed toward the isolation of cactus alkaloids. Certain lay publications are currently promoting various cacti as "natural and legal" psychedelics and provide their readers with the addresses of cactus dealers who are unwittingly selling the plants for nonhorticultural purposes. The proposed research will attempt to isolate and characterize alkaloids from a list of selected cacti. The objectives will be to verify physiological activity in various "peyote" cacti, to look for mescaline in cacti that are or might be subject to abuse, and to search for new cactus alkaloids that might be psychotropic.